A great many electronic devices are powered by rechargeable batteries. Perhaps the best example of which is a typical cellular telephone. Because of the power consumption of a cellular telephone, rechargeable batteries are a much lower cost means of powering the telephone than using primary, or nonrechargeable batteries. Accordingly, a great deal of work has been done in the battery and battery charger arts. Presently, a number of manufacturers have designed and sell rechargeable battery packs, or simply batteries, that include electronic digital memory devices. The information stored in these memory devices includes battery parameters to allow the charger to select an optimal charge regime for the particular type of battery.
At the same time, people have become more dependent on devices such as cellular telephones, and often leave them on as much as possible. Since the battery must periodically be recharged, manufacturers have designed battery chargers that will accept the battery while it is connected or attached to the host device. In this way, the user can leave the device on so as not to miss any incoming phone calls.
Once the battery and the attached device are placed into the battery charger, the battery charger can commence charging the battery according to the information read from the battery memory. At the same time, it is desirable to take certain actions in the host device, such as turning off the display of the battery fuel gauge, and turning on keypad backlights, for example. Since the battery is being charged, there is no need to worry about draining excess current from the battery, as when operating the device away from the battery charger. However, the host device needs to be able to detect the presence of the battery charger before any such actions can be taken. Therefore, there is a need for a method for an electronic device to detect the presence of a battery charger, so that the electronic device can take actions such as turning off display segments. Furthermore, there is a need for the device to be able to detect the removal of the battery charger, so that high current drain activities may be minimized so as to prolong the operation time afforded by the battery.